AS an avid reader of fairytales in my youth, I was always intrigued by the story of the seven ravens. Seven princely brothers condemned to be ravens by day can only be rescued if their beautiful sister is prepared to pick nettles, barehanded, spin them into thread and weave the lot into seven shirts. Unfortunately she gets imprisoned as a witch but carries on calmly sewing the shirts even as they light the pyre beneath her. AS the flames lick around her skirts, she flings the shirts onto the ravens who immediately are restored to human form (except the youngest whose shirt was missing a sleeve …it was that or the lot go up in flames with her…so he gets stuck with a black wing) and THEN they rescue their sister from her awful fate.

So that’s how at the age of 10, I knew you could make nettles into cloth… and apparently they still do but in very small quantities. However at age 10, I personally knew them the hard way…being stung regularly where I grew up. Yet there was always a dock leaf to hand.

So my questions to you today are: did you know its Nettle Awareness Week again (NAW, May 17-25) and secondly, where have all the dock leaves gone?

Last year’s NAW & associated events was blogged about by a colleague (Taking the sting out of nettles). I heard about it from Midweek (May 14, Radio 4): here we had the cooks revenge (nettle soup), a reminder that nettles are essential to wildlife (think caterpillars), nettles for medicinal purposes, and that passing mention of nettles for cloth. Oh and apparently most of the nettles go to Japan.

What do our databases CAB Abstracts and Global Health have to say on this multipurpose plant, can they tell us anything else we could use nettles for or even why rabbit loos (latrines) are always covered in nettles? Can nettles be used for carbon trading or bioremediation and just who are these people using it for cloth? Is Nettlebed, Oxfordshire, named after an association with the cloth trade???..well ok our databases don’t cover the study of place names but they do make interesting reading on nettles.

First those stinging hairs: it used to be thought they injected formic acid but actually it’s a mixture of histamine (hence the reddish weal of nettle rash), acetyl choline and serotonin. HanYi et al (1) tell us that Urtica thunbergia, a relative of our common stinging nettle, U. dioica, injects oxalic acid and tartaric acid to cause the long-lasting pain. The stinging hairs on nettles are really there for defence from grazing animals such as deer and in heavily grazed areas the nettles have more stings (2)!

Nettles are grown commercially as medicinal herbs (e.g. Turkey) for both human and veterinary purposes. Most recently extracts have been tested for nematicidal activity (3) against Haemonchus contortus which affects cattle and as an immunomodulator for lupus erythematosus (4).They even get into our shampoos but in the past much better use was made of them – particularly in war time – as a food, for they are an excellent source of Vitamin C and folic acid, high in protein. You have to use young nettles & cook them to eliminate the sting, so take care. In the Global Health Archive, I found that carotene from nettles had been used as a source of Vitamin A for margerine in 1936 (5) and in Russia in 1934 (6) they were being used as green feed for poultry, silage for cattle and for fibre production . In 1941, there was a report of breeding work (7) to increase the fibre content and improve seed oil yields…perhaps I should hope for a revival for it on the herbalist shelves alongside poppy and hemp oil. Returning reluctantly to 2008 (well its fascinating to find that Serbian gypsies made carrion edible by steeping it in water containing nettles) I found that nettle oil has been shown ineffective against liver fibrosis in an animal model (8) but shows great promise as a substitute for antibiotic growth promoters being phased out in animal production (9).

Nettles provide homes for both crop-friendly and pest insects, such as planthoppers (10), yet also offer solutions to the pests. One particular nettle extract has potential to control the aphid Myzuz persicae by reducing its fecundity (11), whilst nettles growing in field margins, though providing a haven for aphids which affect crops have also proved to be a way to control them: just ensure those on the nettles have the aphid-pathogenic fungus Pandoraneoaphidis infecting them(12)!

AS for Nettlebed, nettle linen may well have graced English C18 homes nearby but it took the second world war for the UK to reinvestigate it for producing fibre for cloth, and for use in compost. A revival in clothmaking is now happening through a Dutch company interested in sustainability (apparently cotton production is very heavy on pesticide use) (13).

And I haven’t forgotten bioremediation. Yes, nettles are being investigated for this too…a conference paper was given in 2003 (14) on this subject.

So MUCH RESPECT to Nettles…but still unanswered is the question of where have all the dock leaves gone…you can never find one near the nettle patch these days.

Welcome

CABI is an international not-for-profit organization that improves people’s lives worldwide by providing information and applying scientific expertise to solve problems in agriculture and the environment.